Slip rings are commonly used in a variety of applications to transfer electrical energy, including electrical power and/or signals, over one or more channels between portions of an apparatus which experience relative rotation. As a non-limiting example, slip rings may be used in a variety of downhole applications as components of apparatus which are adapted to be inserted within boreholes. Such apparatus may include without limitation, borehole drilling apparatus, wellbore completion apparatus, wellbore logging apparatus, and/or wellbore production apparatus.
A challenge in the design and operation of slip rings is maintaining the electrical contact between the components of the slip ring while the slip ring is in use, due to movement and/or vibration of components of the slip ring, due to movement and/or vibration of components of the apparatus in which the slip ring is used, or due to other causes. Such other causes may relate to the environment in which the slip ring is operating.
As one example, a slip ring may be immersed in a dielectric fluid during its operation. The dielectric fluid creates the potential for a “hydroplaning effect” in which the dielectric fluid may cause the components of the slip ring to lose contact as they rotate relative to each other. The potential hydroplaning effect tends to increase with the viscosity of the dielectric fluid and with the relative speed of rotation between the components of the slip ring. An increased viscosity of the dielectric fluid is a risk factor for “viscous hydroplaning.” An increased relative speed of rotation is a risk factor for “dynamic hydroplaning.”